How to connect Arduino Uno WiFi to ThingSpeak

I took on this little project as a proof of concept for IoT devices. My main goals were to find the easiest, cheapest way to stream data to the cloud. This article describes how to stream telemetry data to ThingSpeak via REST API. This can also be done with Azure IoT hub with a local gateway.

1) What you need

DHT22 – Temperature/Humidity Sensor

MH-RD – Snow/Raindrop Detection Sensor

YL-69 – Soil Moisture Sensor

Arduino UNO WiFi connected to WiFI with internet access

Resistor 10k Ohm

Battery Pack

ThingSpeak Account with a channel configured

Arduino IDE

Any waterproof enclosure big enough to fit components

2) Fritzing Diagram

3) Sketch

a) After connecting all the sensors and cables as per the diagram above, open the Arduino IDE and copy and paste this into a new sketch.

#include <Wire.h>
#include <DHT.h>
#include <UnoWiFiDevEd.h>

#define CONNECTOR     "rest"
#define SERVER_ADDR   "api.thingspeak.com"
#define APIKEY_THINGSPEAK  "****************" //Insert your API Key

void setup() {
  Ciao.begin();
}

void loop() {
  DHT dht;
  dht.setup(2);

  String uri = "/update?api_key=";
  uri += APIKEY_THINGSPEAK;
  uri += "&field1=";
  uri += String(dht.getHumidity());
  uri += "&field2=";
  uri += String(dht.getTemperature());
  uri += "&field3=";
  uri += String(analogRead(A0));
  uri += "&field4=";
  uri += String(analogRead(A1));

  Ciao.println("Sending data on ThingSpeak Channel");
  CiaoData data = Ciao.write(CONNECTOR, SERVER_ADDR, uri);

  if (!data.isEmpty()){
    Ciao.println( "State: " + String (data.get(1)) );
    Ciao.println( "Response: " + String (data.get(2)) );
  }
  else{
    Ciao.println("Write Error");
  }
  delay(900000);
}

b) Change the ThingSpeak API to you channel API

c) Plug in Arduino Uno and hit CTRL+U to upload sketch to device